Genetically programming cells require sensors to receive information, circuits to process the inputs, and actuators to link the circuit output to a cellular response (Andrianantoandro E, et al., Mol Syst Biol 2 (2006); Chin J W Curr Opin Struct Biol 16: 551-556 (2006); Voigt C A Curr Opin Biotech 17: 548-557 (2006); Tan C, Mol Biosyst 3: 343-353 (2007)). In this paradigm, sensing, signal integration, and actuation are encoded by distinct ‘devices’ comprised of genes and regulatory elements (Knight T K, Sussman G J Unconventional Models of Computation 257-272 (1997); Endy D Nature 438: 449-453 (2005)). These devices communicate with one another through changes in gene expression and activity. For example, when a sensor is stimulated, this may lead to the activation of a promoter, which then acts as the input to a circuit.